How the sand of the beaches appear
Have you ever wondered how the sands of the coast appear? Well, we will explain quit succinctly how the sand, one of the most striking components of the beaches, is formed.
Sand grains of dimension ranging from 2 to 0.05 mm are formed by the same principle that in part explains the formation of soils, that is, the fragmentation of rocks form the hills and mountains and/or others regions by the action of weathering.
Wind, rain and plant roots that penetrates the rocks are all agents of physical weathering, which means that the exposition of rocks to those natural agents results on the formation of smaller particles, like sands. However, do not think that this happens from day to night, it is a very slow process needing millions of years.
The rock of the mountain is the factor that determines which sand will predominate on the beach. For example, beaches with white sands are formed by quartz particles, a silica mineral present in abundance in acidic igneous rocks such as granite that is the principal component of the planet’s continental crust.
On the other hand, the darker sand strips that occur on some beaches can be constituted by ilmenite, an iron and titanium oxide (FeTiO3). The titanium oxide, such as quartz, is very resistant to chemical dissolution, being able to accumulate as mineral of sand fraction in soils and sediments.
Not all the rocks are fragmented on the same velocity, because the rocks fragmentation speed and consequently the formation of smaller particles, like sand, depends on the chemical components and genetic structure of the rock.
So far so good, right? But, then comes another question: how sand is transported from mountains to the coast? Well, the path traveled by these mini particles is long. Under the action of the wind, rain surface runoff and of course, of the gravity, the rock sediments are goes down the hill and leave the mountain surroundings carried by the rivers in a journey towards the sea.
The rivers are responsible to do the separation of the clay, sand and gravel fractions. Clay, due to its smaller density, is suspended in water, instead gravel is deposited on the bottom of the rivers and sand, due to its physical attributes, has the ideal size to be transported by the flow, being able to undergo changes in its form (getting smaller and more rounded) during its path. As the rivers flow into the sea, finally, the sands arrive at their final destination, the coast! So, the sand is deposited as sediments of bottom or beaches.
Over the course of time (a few millions years), the sand of the beaches can be covered by other sediments and, with the increasing of pressure, can be transformed, for example, into a sandstone. The set of processes that transform sediments into sedimentary rocks is named diagenesis.
So, after this reading, your summer on the beach will not be the same, right?
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